We have several different uses of marry and married in play. Some of the meanings deal with an act and others with a status.
There are two basic uses of marry, both relating to the act:
[transitive or intransitive] to become the legally accepted husband or wife of someone in an official or religious ceremony:
[transitive] to perform the ceremony of marriage as a priest or official:
(most of the additional uses you will find in a dictionary, as to acquire something through marriage as in marry money, or to find a spouse, as in marry her daughter to the prince, derive from the first).
There are two non-overlapping senses of married, the first referring to the status, the second referring to the act:
having a wife or husband
to begin a legal relationship with someone as their husband or wife
The act of becoming a husband or wife (i.e. taking vows, participating in a wedding ceremony, signing legal papers, et al), represented by the first meaning of marry and the second meaning of married, is usually expressed as getting married. Thus, a native speaker would be more likely to say
I am getting married in July.
I will get married in July.
Congratulate me, I'm getting married.
Congratulate me, I'm going to get married.
You can say
I am to be married in July.
but like all I am to V statements (I am to be named chief, I am to take the pills daily), it is formal and sounds somewhat stiff.
Usually, to say being married in referring to the act is usually to use the second sense of marry in the passive voice.
Parson Brown will marry us on Saturday. → We are being married by Parson Brown on Saturday.
Otherwise, being married is often in the first sense of married, to be in a state of marriage with someone.
Being married to someone for 20 years takes patience and sacrifice.